Chordomas and chondrosarcomas of the spine commonly extend into the spinal canal and impinge on the dura and cord. During resection, the lesion is peeled from the dura, resulting in positive margins. With current external beam radiation therapy, the tumor bed can be effectively treated. However, because the distance between the dura and cord surface is only 2 to 2.5 mm, dose to the dura must be limited to a suboptimal level. To increase the dose to the dura without over-irradiating the cord, it is proposed to intraoperatively deliver a supplemental dose using a radioactive beta-emitting plaque. With this plaque, dose to the cord surface would be only 10 percent of the dose to the dura and the dose to the mid portion of the cord would be substantially less. The additional dose delivered will markedly increase the probability of tumor control. The specific aim of this program is to develop a novel beta-emitting brachytherapy plaque for intraoperative irradiation of the dura. Two different beta-emitting radionuclides will be tested and their dosimetry will be evaluated for clinical utility. The results of this evaluation will lead to an optimum design of this plaque, which will be bench-tested in preparation for clinical trial. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE